java.lang.Object
javax.swing.text.AsyncBoxView.ChildLocator
- Enclosing class:
AsyncBoxView
A class to manage the effective position of the
child views in a localized area while changes are
being made around the localized area. The AsyncBoxView
may be continuously changing, but the visible area
needs to remain fairly stable until the layout thread
decides to publish an update to the parent.
- Since:
- 1.3
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Field Summary
Modifier and TypeFieldDescriptionprotected Rectangle
A shape to use for the child allocation to avoid creating a lot of garbage.protected Rectangle
The last seen allocation (for repainting when changes are flushed upward).protected AsyncBoxView.ChildState
The location of the last offset calculation that is valid. -
Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionvoid
Notification that a child changed.protected Shape
getChildAllocation
(int index) Fetch the allocation to use for a child view.getChildAllocation
(int index, Shape a) Fetch the allocation to use for a child view.int
getViewIndexAtPoint
(float x, float y, Shape a) Fetches the child view index at the given point.protected int
getViewIndexAtVisualOffset
(float targetOffset) Locate the view responsible for an offset into the box along the major axis.void
Paint the children that intersect the clip area.protected void
Copy the currently allocated shape into the Rectangle used to store the current allocation.
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Field Details
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lastValidOffset
The location of the last offset calculation that is valid. -
lastAlloc
The last seen allocation (for repainting when changes are flushed upward). -
childAlloc
A shape to use for the child allocation to avoid creating a lot of garbage.
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Constructor Details
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ChildLocator
public ChildLocator()construct a child locator.
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Method Details
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childChanged
Notification that a child changed. This can effect whether or not new offset calculations are needed. This is called by a ChildState object that has changed it's major span. This can therefore be called by multiple threads.- Parameters:
cs
- the child state
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paintChildren
Paint the children that intersect the clip area.- Parameters:
g
- the rendering surface to use
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getChildAllocation
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getViewIndexAtPoint
Fetches the child view index at the given point. This is called by the various View methods that need to calculate which child to forward a message to. This should be called by a block synchronized on this object, and would typically be followed with one or more calls to getChildAllocation that should also be in the synchronized block.- Parameters:
x
- the X coordinate >= 0y
- the Y coordinate >= 0a
- the allocation to the View- Returns:
- the nearest child index
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getChildAllocation
Fetch the allocation to use for a child view. This does not update the offsets in the ChildState records.- Parameters:
index
- the index- Returns:
- the allocation to use for a child view
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setAllocation
Copy the currently allocated shape into the Rectangle used to store the current allocation. This would be a floating point rectangle in a Java2D-specific implementation.- Parameters:
a
- the allocation
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getViewIndexAtVisualOffset
protected int getViewIndexAtVisualOffset(float targetOffset) Locate the view responsible for an offset into the box along the major axis. Make sure that offsets are set on the ChildState objects up to the given target span past the desired offset.- Parameters:
targetOffset
- the target offset- Returns:
- index of the view representing the given visual location (targetOffset), or -1 if no view represents that location
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